1. Field of the Invention
This invention relates generally to sealing mats comprising flexible sheets carrying plugs or septums for sealing arrays of test tubes and the like, and is concerned in particular with an improvement in the manner in which the plugs or septums are detachably secured to the carrier sheets.
2. Description of the Prior Art
In a known sealing mat of the type described, for example in WO 01/17682 A1 (Wijnschenk), a matrix of hole is punched through a thin flexible carrier sheet. Plugs are then injection molded into the holes of the sheet. The plugs are formed with circular flanges that are grooved to accept edge portions of the holes, resulting in the plugs being detachably secured to the sheet.
There are several drawbacks with this approach. The attachment of the plugs to the carrier sheet is somewhat tenuous, thus raising the risk of premature plug separation if the carrier sheet is inadvertently flexed. The plug flanges are weakened by the grooves provided to straddle the edge portions of the holes in the sheet. This in turn can result in the plugs being forced into the tubes when they are being pierced by aspiration needles. The weakened flanges also make it more difficult to remove the plugs from the tubes.